On Aug. 2, EPA issued its assessment of the potential benefits and costs of meeting the standards in its proposed revisions to the nation's air quality standards for ground-level ozone. EPA has proposed to strengthen the standards, based on the most recent scientific evidence about the health effects of ozone -- the primary component of smog.

This assessment, known as a Regulatory Impact Analysis (RIA), provides general estimates of the nationwide benefits and costs of reaching a standard in the EPA proposed range, which is 0.070 to 0.075 parts per million (ppm). The current ozone standard is 0.084 ppm. The RIA also looks at the benefits and costs of reaching a standard at two other levels within the range of standards that EPA has requested comment on, 0.065 ppm and 0.079 ppm.

To estimate the benefits of meeting alternative standards, EPA uses peer-reviewed studies of air quality and health and welfare effects, sophisticated air quality models, and peer-reviewed studies of the dollar values of public health improvements.

The RIA is intended to inform the public about the relative magnitude of the potential benefits and costs of reducing pollution to meet alternative ozone standards. It also illustrates emissions control strategies states might consider adopting to meet the revised standards in an efficient and cost-effective manner. For some urban areas, the analysis assumes that future innovation and technological advances will enable states to achieve the proposed standards by 2020.

EPA did not use this analysis in selecting the proposed ozone standards; the Clean Air Act bars the agency from considering costs in setting any national ambient air quality standard. EPA conducted the analysis under other requirements that the agency analyze the benefits and costs of any major regulation.

This article originally appeared in the 08/01/2007 issue of Environmental Protection.